Towards a mechanized metatheory of standard ML

Abstract

We present an internal language with equivalent expressive power to Standard ML, and discuss its formalization in LF and the machine-checked verification of its type safety in Twelf. The internal language is intended to serve as the target of elaboration in an elaborative semantics for Standard ML in the style of Harper and Stone. Therefore, it includes all the programming mechanisms necessary to implement Standard ML, including translucent modules, abstraction, polymorphism, higher kinds, references, exceptions, recursive types, and recursive functions. Our successful formalization of the proof involved a careful interplay between the precise formulations of the various mechanisms, and required the invention of new representation and proof techniques of general interest.

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Index Terms

• Software and its engineering

  • Software notations and tools

    • Formal language definitions

      • Semantics

      • Syntax

• Theory of computation

  • Semantics and reasoning

    • Program reasoning

      • Program verification

    • Program semantics